The savage nature of the Moors Murderers' killings made them among the most hated criminals in Britain.
The pair began their killings in 1963 after Brady told his girlfriend - who followed him with unquestionable devotion - that he wanted to commit the ideal murder.
He therefore left Keith's family and relatives to live with a devastating unanswered question hanging over them.
Pauline was found still wearing her pink and gold party dress and blue coat.
"I first heard the tape when I was a detective sergeant in Manchester investigating the Moors Murders".
Brady was born Ian Stewart on 2 January 1938, the illegitimate son of a Scottish waitress. The photograph would later lead police to the young boy's resting place.
Brady has also been urged to "do the right thing" and reveal where the last of his child victims is buried.
He became the murderers' third victim when he was abducted after leaving his home in Chorlton-on-Medlock, in Manchester on 16 June that year.
Four of their victims were found buried in Saddleworth Moor.
He said: "Our aim, as it always has been, is to find where Keith is buried and give closure to his surviving family members so they can give Keith the proper burial they so desperately want".
The pair were jailed over the killings of John Kilbride, Lesley Ann Downey and Edward Evans in 1966, before later admitting the murders of Pauline Reade and Keith Bennett.
Keith was lured into Hindley's Mini pick-up as he walked to his grandmother's house in the Longsight area of Manchester.
The murders of John, Keith, Lesley Ann and Edward followed.
Her cries reduced the judge, jury, courtroom spectators and even hardened police officers to tears. Her body was dug up naked except for shoes and socks. He insisted she was as much to blame. The Moors murderers were arrested thanks to Mr Smith. He then fled terrified and called the police. There will only ever be another search if there's fresh evidence.
Mr Stalker added: "The song brings back awful memories of having to listen to a tape of Hindley and her accomplice Ian Brady torturing a terrified little Lesley Ann Downey with that music playing in the background". Brady was also convicted of murdering John Kilbride, 12, with Hindley as an accessory.
The body of Keith Bennett is yet to be recovered, and the police are still hopeful that one day they will be able to effect this.